[bug] [dev] simple_bca_py panics on E1 = 0.0

[drobnyjt]

Description
When simple_bca_py is given E1 = 0.0, it doesn't filter or verify inputs, so it proceeds directly to the DOCA calculation which immediately returns a NaN (because the potential is singular at the origin).

To Reproduce
simple_bca_py(..., E1=0.0, ...)

Expected behavior
Even the library functions should probably panic immediately on bad input instead of panicking on the eventual numerical consequences.